1. The Field of the Invention
This invention is in the field of dispensing devices. More particularly, this invention relates to medical and dental dispensing devices for mixing and dispensing two-part materials to a desired location.
2. The Relevant Technology
Many modern formulations are packaged in two parts, often known as "A and B components" or "first and second materials". Upon mixing, these A and B components typically undergo a chemical reaction which causes the resultant composition to "set up" in some desired manner. In the dental field, for example, several two-part formulations currently enjoy wide use, such as cements and resinous materials. Dental impression materials are also typically made using A and B components.
In order to function properly, the A and B components should be mixed together rapidly and thoroughly and in the right proportions. Failure to mix rapidly can result in loss of valuable working time with the resultant composition, and can impact the ability to obtain a thorough mix as the composition begins to set up unevenly. Failure to mix thoroughly can result in a composition having less than optimum characteristics. For example, if a poorly mixed composition is used as a cement, it is possible that portions of the cement will fail to reach the chemical strength required for a long-term bond.
A typical method employed for mixing A and B components has been simple mechanical mixing through the use of a mixing bowl or pad, and a stir instrument such as a spatula. This method tends to be somewhat messy and time consuming. It is also difficult at times to gauge whether the mixing has been sufficiently thorough.
Further, many dental compositions are ultimately dispensed from a syringe in order to control the amount dispensed, to permit precise placement of the dental composition, and prevent premature evaporation of constituents of the composition. The use of a syringe is highly advantageous for the delivery of a dental composition in light of the ability to easily maneuver a syringe into tight places, such as between teeth and gums. Despite the many advantages of syringe delivery, syringe delivery typically requires the placement of a mixed composition into a syringe, which adds time to the procedure.
Although syringes are highly maneuverable even in tight places, the loss of working time associated with the loading of syringes has caused many practitioners to seek alternative methods for delivering a two-part material into the mouth of a patient For example, in an effort to overcome the time delay associated with placing a mixed two-part composition into a syringe, attempts have been made to mix materials delivered from a caulking gun-type extrusion device.
Typical caulking gun-type extrusion devices comprise a large and bulky device having a receiving area which receives one end of a dual barrel cartridge. Typical dual barrel cartridges have first and second materials therein which are held in separate barrels at a proximal end by movable plugs and which have a selectively closable opening at a distal end thereof. The receiving area also has first and second plungers coupled to a trigger.
Upon coupling the dual barrel cartridge into the receiving area, the plungers are aligned within respective barrels. The practitioner can then actuate the trigger, causing the plungers to advance within the barrels. This forces the first and second materials from respective barrels of the cartridge. A single mixing tube is typically coupled to the exit end of each of the barrels. The first and second materials are typically forced into the mixing tube where the materials are mixed. Typical mixing tubes have a mixing vane therein which is configured to mix the materials upon delivery through the mixing tube.
FIG. 1 depicts a prior art version of such a two-part material dispensing system 10 featuring a caulking gun type extruder 12 having a dual barrel cartridge 14 selectively coupled thereto. The cartridge 14 is coupled to a receiving area 16 of the extrusion apparatus 12. Upon actuating a trigger 18 of the extruder 12, first and second plungers 19 (only one plunger 19 shown) of the extruder 12 advance into respective barrels of cartridge 14, forcing the first and second materials within the first and second barrels of cartridge 14 into a mixing tube 20 having a mixing vane (not shown) therein. The first and second materials expressed from the separate barrels of cartridge 14 are mixed as they proceed along mixing tube 20. The mixed material is then forced out of distal tip 24 of mixing tube 20 and into the mouth of the patient.
As depicted in FIG. 1, the use of the prior art caulking gun-type dispensing system 10 is awkward. The practitioner is required to hold the entire system 10, which is large and cumbersome, adjacent the mouth of the patient, then attempt to deliver first and second materials within cartridge 14 to a specific location within the mouth of the patient. The weight of the dispensing system 10 along with its length and overall bulkiness can combine to make this procedure quite difficult and frustrating both for (i) the practitioner, who is required to hold, aim and actuate the dispensing system 10; and (ii) the patient, who must endure the placement of such a large, bulky instrument adjacent his or her head.
To compound this frustration, the strain accompanying the compression of trigger 18 while holding the bulky system 10 adjacent the patient's mouth can cause the practitioner's hand to shake during delivery of the composition, further decreasing the accuracy of the delivery of the composition into a precisely desired location within the mouth of a patient.
There is therefore, a need in the art for a dispensing system which is readily maneuverable without allowing a two-part material to harden prematurely. There is also a need in the art for a dispensing system which is not bulky and can be readily actuated by a practitioner. There is also a need in the art for a maneuverable dispensing system which can be used to dispense material directly and conveniently into small spaces within the patient's mouth, such as between the patient's teeth and gums without employing a prematurely hardened material.